feat(mcp): add tool presets and audit commands

- Introduce reference MCP presets with installation/audit helpers and remove legacy connector lists.
- Add CLI `owlen tools` commands to install presets or audit configuration, with optional pruning.
- Extend the TUI :tools command to support listing presets, installing them, and auditing current configuration.
- Document the preset workflow and provide regression tests for preset application.

crates/owlen-core/tests/presets.rs

@@ -0,0 +1,61 @@
+use owlen_core::config::Config;
+use owlen_core::mcp::presets::{PresetTier, apply_preset, audit_preset};
+
+#[test]
+fn standard_preset_produces_spec_compliant_servers() {
+    let configs = Config::preset_servers(PresetTier::Standard);
+    assert!(
+        !configs.is_empty(),
+        "expected standard preset to contain connectors"
+    );
+    for server in configs {
+        assert!(
+            server
+                .name
+                .chars()
+                .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-'),
+            "server '{}' failed identifier validation",
+            server.name
+        );
+    }
+}
+
+#[test]
+fn apply_preset_adds_missing_servers() {
+    let mut config = Config::default();
+    let report = apply_preset(&mut config, PresetTier::Standard, false).expect("apply preset");
+    assert!(!report.added.is_empty(), "expected connectors to be added");
+    assert!(report.updated.is_empty());
+    assert!(report.removed.is_empty());
+
+    let audit = audit_preset(&config, PresetTier::Standard);
+    assert!(
+        audit.missing.is_empty(),
+        "expected no missing connectors after install"
+    );
+}
+
+#[test]
+fn prune_preset_removes_extra_entries() {
+    let mut config = Config::default();
+    // Seed with an extra entry
+    config
+        .mcp_servers
+        .push(owlen_core::config::McpServerConfig {
+            name: "custom_tool".into(),
+            command: "custom-cmd".into(),
+            args: vec![],
+            transport: "stdio".into(),
+            env: Default::default(),
+            oauth: None,
+        });
+
+    let report = apply_preset(&mut config, PresetTier::Standard, true).expect("apply preset");
+    assert!(report.removed.contains(&"custom_tool".to_string()));
+    assert!(
+        config
+            .mcp_servers
+            .iter()
+            .all(|srv| srv.name != "custom_tool")
+    );
+}